Apparatus for preparation of rotogravure cylinders



R. A. DIEHM Sept. 19, 1950 APPARATUS FOR PREPARATION OF ROTOGRAVURE CYLINDERS Filed May 5, 1947 J72 0622 for E05 er? .1. fiz'ez%m @W m fltarn ys.

Patented Sept. 19, 1950 APPARATUS FOR PREPARATION OF ROTO- GRAVURE CYLINDERS Robert A. Diehm, Riverside, Ill., assignor, by mesne assignments, to lPaper Patents Company, Neenah, Wis., a corporation of Wisconsin Application May 5, 1947, Serial No. 746,108

u 1 Claim.

My invention relates to improvements in method and apparatus for preparation of rotogravure cylinders. It has for one object to provide a new and improved apparatus and process which will produce rotogravure cylinders with a minimum waste of material, and will result in the production of accurate, clean-cut printing members.

As is well known, acid etching is used in the production of rotogravure cylinders, and it is of the utmost importance that when the acid has done its work it be removed without delay, as otherwise cylinders are inaccurate, unsatisfactory, and even spoiled. Much work has been done in connection with the removal of the acid. It is neccessary that the acid be removed quickly, expeditiously and completely, and that in the removal the plate or cylinder itself be not mechanically abraded and that no acid be left on the plate or cylinder after the time that the etching has been accomplished.

I propose to bring about this acid removal by the use of what is referred to in the trade as an air knife or doctor bar. Air knives and doctor bars have been used for spreading liquids on surfaces, even for cleaning surfaces under some circumstances, but I have found no case where such apparatus had been used or proposed to be used in connection with the removal of the etching acid from a plate or cylinder in connection with the rotogravure or similar printing processes.

My invention is illustrated more or less diagrammatically in the accompanying drawings, wherein:

Figure 1 is a side elevation of an apparatus embodying my invention;

Figure 2 is a section along the line 2-2 of Figure 1;

Like parts are indicated by like characters in the specification and drawings.

l, 2 are end-supporting frames. Each of them carries a journal box 3 having a removable cover 4. The boxes 3 support a roller shaft 5, each end of the shaft being supported in one of the boxes and held in place by the removable cover 4. 6 is a roller carried by the shaft, on which is removably mounted a rotogravure cylinder 1. 8 is a sprocket on one end of the roller shaft 9 a drive chain engaging the sprocket 8 and driven by a drive sprocket l0 driven in turn by a motor H, whereby the cylinder may be rotated. 12 is an acid trough supported between the end frames 1 and 2 immediately beneath the roller. The acid trough has walls l3 extending up to and terminating immediately adjacent, but out of actual contact with, the cylinder. I4 is an agitator paddle contained within the trough l2, mounted on a shaft [5 extending outwardly through the end of the trough I2, the shaft 15 being equipped with a sprocket l6 driven by a chain I! from a sprocket l3 driven by the motor ll, so that as the cylinder rotates, the agitator rotates in unison therewith but at a higher rate of speed, and agitates and throws the acid against that part of the cylinder open downwardly to the acid trough between the walls l3. I9 is an air knife mounted on the end frames 2, having a narrow discharge nozzle 20 discharging against the face of the roll and plate. The axis of discharge of air through the nozzle 26 as it extends across the entire length of the plate is inclined against the direction of rotation of the cylinder, so that the air tends to strip the acid from the cylinder, blowing it back downwardly toward, and causing it to fall into, the trough 2!. In the trough 2! is a spray pipe 22 which sprays water upon the cylinder to dilute the acid. The water and acid, removed from the cylinder by the air knife, falls into the trough 2| and may be returned to the acid trough [2 if desired, or may be concentrated, by a simple means not here illustrated as it forms no part of the invention, before the acid is returned to the acid trough. 23 is a high-pressure air supply pipe adapted to supply air to the air knife, air, under high pressure, being supplied to this pipe from any suitable source of supply not here illustrated. The valve 2 is adapted to control the air pressure.

The photographic and chemical processes resulting in the production of a rotogravure cylinder form no part of my present invention. My invention is limited to the method and process of removing the excess acid from the cylinder. It will be understood, of course, that there are many other printing industry situations where the use of the air knife and the use of the apparatus which I disclose are important. I have illustrated my apparatus and process in connection with a cylinder or rotated curved plate. Obviously a flat plate might equally efiectively be treated, in which case, of course, the plate would move along a straight line instead of along a curved path across the mouth of the acid trough.

I claim:

In combination in an etching machine for etching the peripheral surface of a printing cylinder, a longitudinally extending etching trough adapted to contain etching fluid, having at its top an open mouth, means for rotatably supporting the cylinder to be etched above the trough with its longitudinal axis generally parallel to said open mouth, said support means for the cylinder to be etched being at such height above the trough that the open mouth of the trough is closed by the peripheral surface of the cylinder to be etched, there being sufficient clearance between the upper wall of the trough and the peripheral surface of the cylinder to prevent contact therebetween, means for rotating the cylinder, a washing trough extended along the etching trough, bounded on one side thereby and extending upwardly about a portion of the peripheral surface of the cylinder being etched, means within the washing trough for projecting awash-' ing spray against the periphery of the cylinder '15 Number being etched along a generally tangential path toward the etching trough in a direction opposite to the direction of rotation of the cylinder, means adjacent the upper edge of the Washing'trough for projecting a generally tangential air jet 20 2,360,676

tion of the cylinder, and means within the etching trough for projecting the etching liquid against the peripheral surface of the cylinder to be etched.v

ROBERTA. DIEHM.

REFERENCES CITED The. following references are of record in the tile 01 this patent:

UNITED STATES PATENTS Name Date 1,001,031 Hilliard Aug. 22, 1911 1,166,378. Levy Dec. 28, 1915 1,371,338 Andresen Mar. 15, 1921 2,293,201 Gaebel Aug. 18, 1942 Henderson Oct. 17, 1944 

